


A fist of DETERMINATION

by Bobari



Category: One Piece, Undertale (Video Game)
Genre: Gen, i always thought writing fanfiction was easy but hell
Language: English
Status: In-Progress
Published: 2015-12-04
Updated: 2015-12-04
Packaged: 2018-05-04 20:15:09
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,673
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5347175
Author URL: https://archiveofourown.org/users/Bobari/pseuds/Bobari
Summary: <blockquote class="userstuff">
              <p>We usually see Frisk as the pacifist, hug-it-out kinda person, but I always wanted to see Frisk loving fights and enjoying them. And somehow instead of Frisk Luffy fell down the hole. I don't know? Come on, if he was near Ebott, he would be the first to jump.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> While I tried to form the idea into words, all the sophisticated concepts came out as "he walked, he fought, Luffy happy, rowwr". I'll get better (well, with the help of good wishing and prays and practice), soo if you are interested in the idea, please bear with me for a while?

...and so the monsters were sealed underground. Legends also say that those who climb the mountain never return.

A beat.

"...monsters?"

A slow turn of head.

"...underground down a mystery hole?"

Sparkles from the eyes, so many sparkles:

"...never return??"

Without wasting any time, Luffy grabbed his hat and jumped down the tunnel.

Who cares; he was walking around this mountain lost for the last 3 hours anyway. Other adventures could wait.

***

"Howdy!"-said the flower,-"I'm Flowey. Flowey the Flower."

"And I'm Luffy, the man who is going to be Pirate King! Are you a talking flower? You should think up some new name, yours is stupid." - Luffy's voice was lacking the usual enthusiasm. Well, he has seen drinking trees, so talking flowers weren't such a stretch.

The flower lowered its head consdensingly. Oh the newbyes, always the same! (if you ignore the nonsense with the Pirate King, and what's that anyway?) Why change the script, when everything is so predictable?

"You are new..."

"Hey, flower, where are the monsters? Are they strong? Do you have any food? I'm seriously hungry." Being rude was always forgiven, when one was hungry, right? And Luffy was so hungry; walking around the mountain for 3 hours took its toll on him.

Flowey's usual spiel needed some improvisation apparently. It was easy to see the needed corrections:the teen was already drooling in Flowey's grass patch. Gross.

"Sure! I'll tell you everything you want. But first ...food there is given through special love pellets." 

Flowey was feeling even more ridiculous than usual. Better get it over with.

"The more love you have, the less hungry you are! Do you want some L..FOOD?"

Did his eyes just turn to meat?

"Sure! Can you give me lots of meat? Like, meat pellets? Ooooh, are your pellets made out of meat? YOU CAN PRODUCE MEAT??"

***

At the last moment, Luffy avoided the pellets, scraping up the dirt once more. Flowey frowned, but immediately put the smile back on.

"Well, aren't you clumsy! Why don't we try again? Catch the pellets, if you want...hey, what's with that expression?"

This time, the teen didn't wait at all, choosing instead to jump right to the space near Flowey. He cracked his fingers, looking pissed and perplexed at the same time:

"You know, I don't really get why...But I really want to punch your face!"

Flowey looked appropriately alarmed.

"You lied about food, I know!" - Luffy was decidingly more pissed now.

Even though the confrontation didn't go the way it was planned, Flowey was too annoyed to diffuse the situation.

"Heh....of course, boy!" - Flower finally lost his composure, surrounding Luffy in pelletes. - "In this world..it's killed or be killed!"

Luffy lowered his stance, raising fists. He smiled wildly:

"Well, bring it on!"

***

"Oh, you are a goat lady. Like those guys on Skypea! Where are your wings? Did you also fall from the sky?"

"Are you...flirting with me?"

***

"My child, I should test your independence. Stay there!...I said stay there, child. I have some things to do. Don't follow me, please."

Luffy pouted, while Toriel patted his hat and ran out of the room. He looked around.

"Eeeeh, it's boring."

Well, he shouldn't follow her, so he should just go somehere else, right?

***

The first Froggit he met on the way went kind of unnoticed. So did the second one. His enemies were probably surprised, when human fleed every time he got chance to, but, well, Luffy didn't exactly bother with understanding the fight menu system. What was EXP anyway?

So the first enemy that didn't let him 'flee' came as a kind of suprise for both sides.

"Sooo...you want to fight?"-Luffy considered the evil-looking carrot. It didn't look so strong, but you should never underestimate your opponent. He himself was the example of that!

As it turned out, not in this case.

"You wanna fight more?" - the teen asked, shaking off some carrot mush from his hands. The enemy hastily went away, taking teen's question as the spare choice. Did he even know how to fight in this world at all, the barbarian? 

"Oh well. Anyway, I get the feeling I've been there before! It's a mystery room, huh? These puzzles sure are confusing."

***

***It seems reluctant to fight you.**

Luffy stopped fighting immediately.

Froggit pitifully croaked, looking to end the fight as fast as possible.

***It is trying to run away.**

"Where are you? Who are you? I can hear you in my head!"

Froggit used the chance to escape. The teen paid him no attention at all.

***You gained..**

"Yeah, you! Who are you,mystery voice?" - Luffy jumped up and down, as if it would help him find the source of the it.

***Are you aware of me? I'm...your friend. I'll help you fight and..**

"Hell no! "- Luffy frowned, crossing his eyes, trying to look inside his own head. Arguing with a voice in his head was kind of hard, but there was no chance he would give up. "This is my body, so I will fight! Alone!"

The voice took on a silky quality.

***But you don't kill them.Why don't you try finishing the fight completely?**

Luffy cocked his head to the side, waiting for some clarification.

***What if they return and try to kill us? They are backstabbing creatures. You should know that, human. So don't give them the chance.**

Luffy looked puzzled for a second, but then laughed rather loudly. It sounded strange in an empty hall, but he didn't mind it.

"I thought you were strong, but you are just a scaredy-cat!"

He continued laughing, while walking down the path. The voice in his head said nothing, starting instead a horrible headache-inducing noise.

"Oi, stop that! I'm strong, so we don't need to kill anybody! We will fight them again, if it comes to that, and win again. And stop with that haunting noise, so annoying!"

The noise stopped for a while, and so did the commentaries. Luffy counted that as a win.

***

***The sight of it fills you with determination. Save?**

"Save what?"

**Just...save. It will help you later.**

"Meh. Looks like too much trouble."

***WHAT TROUBLE JUST PUSH THE BUTTON IN YOUR HEAD AND WHERE ARE YOU GOING YOU..!!**

***

***The size of the pie intimid...oh, never mind.**

***  
"My naive child...If you go to the Ruins...They...Asgore...Will kill you."

Toriel took Luffy's smaller hand in hers, trying to will him to stay there. She looked truly troubled by what she was saying. Luffy was only getting weirdly excited.

"Eh, so those are the monsters I heard about? Don't worry, goat lady, I'm strong! I will defeat them!"

She looked near tears, even though some questions arised in her head("Monsters he heard about?..").

"My child...I'm only protecting you."

Luffy stubbornly looked on. With a sigh, Toriel turned around.

"Then...prove yourself. Prove to me you are strong enough to survive!"

Luffy cocked his head.

"So...I just need to defeat you, and you will let me go through the mystery door?"

Toriel smiled crookedly.

"Yeah..if you can."

***

***Toriel prepares magical attack.**

The voice sounded almost gleeful. For the first time since their awakening, their host would finally get some beating. Even though they had no body, there are some truly satisfying things to watch.

Luffy jumped to avoid fire damage.

"Goat lady, come on! I proved that I'm strong, right? I don't want to seriously hurt you, you gave me food!"

***Toriel looks aloof.**

"Oh, shut up!"

***

Luffy panted, staring at the bleeding, but still standing Toriel. She didn't look like the person about to give up.

"Goat lady, don't be so stubborn! You have to heal yourself! You can do that, right?"

Toriel looked away and raised her hands, already covered in fire.

"Give up, child. You cannot survive up here."

***You have to deal the deciding blow. You have to go through her.**

Luffy barely dodged the attack.

***You are a human, aren't you? You have determination enough. Do it.**

*** K I L L   H E R.**

Mugiwara captain growled, suddenly stopping under the influx of atacks. Toriel panicked, trying to stop them, but she wasn't fast enough. Her eyes widened in fear, hands instinctively flying up to cover up her cry.

"My child!!"

The damage was significant, but young man didn't seem to care about that at all. Patting down some fire on his clothes, he looked up, lifting up the brim of the hat a little.

He looked absolutely furious.

"I've had enough! Mystery voice, shut up for a second!"

Luffy walked up to the still shocked still Toriel.

"And you, lady! You know you can't win! You know I'm strong! Let me go already, or go with me!"

He huffed, crossing arms on the chest. People shouldn't be so stubborn!

Irony, as usual, escaped him.

Toriel let out a quiet sob.

"I cannot go with you, child. I just can't see the death anymore...I.."

She fell down on her knees and suddenly pulled hin into a tight embrace.

"Be good there, my child. I'll let you go. But please...don't come back.You understand?"

Luffy looked at her tear-filled eyes.

"No, I don't!"

He fiercely returned the embrace, choking Toriel a little.

"I'll go, find some monsters,defeat that jerk you talked about and return, goat lady. So stay there and wait for me, I'll definitely come back!"

With that decided, he opened the door. Honestly, why make such a big deal out of it? She should have just gone with him. Maybe she was scared of that As-something guy?

Now that he thought about it, maybe he should worry about finding his way back to the surface....but first, he should find some food and beat up some monsters. Where are the scary guys anyway?  
***


	2. Chapter 2

“The islands in the north~are so cold~”

***Oh god, will you shut up.**

“They shiver all around~And they are all idiots~”

***Aren’t you cold? It’s snow all around, and you have only singed vest and shorts.**

Luffy stopped on his way. He dropped the tough-looking branch and shivered. “Ah! It’s cold! Why didn’t you say so earlier?”, - he jogged on the place, trying to warm himself.

The voice only sighed.

***It looks like there’s a town after that bridge. Warm town. With food.**

“Yosh! Let’s go there!” – the teen ran to the bridge, shaking all the while,  -  “You’re really clever, mystery voice!”.

***Stop calling me mystery voice. I’m…**

“Human. Don’t you know how to greet a new pal?” – somebody interrupted, “Turn around and shake my hand.”

***

Sans considered the human before him. It was a human, right? Even though it was bigger and less scared than usual. The hand in his bony grasp was icy-cold, but the grip was firm. The human was surprised to hear the whoopee cushion noise, but didn’t show any signs of annoyance. A good run this time, huh?

“Hehehe…The old whoopie cushion in the hand trick. It’s ALWAYS funny.” – a human snickered in agreement, - “You are a human, right?”.

The human smiled wildly. “Yeah! I’m Luffy and I’m going to become Pirate King! Who are you? Are you a relative of Brook? Did you eat a Devil Fruit too?” - somehow, this time the meeting diverged from the usual track.   Maybe he should go with the flow.

“I’m Sans. Sans the skeleton. I’m actually supposed to be on watch for humans right now. But. . . y’know…I don't really care about capturing anyone. Now, my brother, Papyrus. . . he's a human hunting FANATIC.” – he made a pause, trying to gauge human’s emotions. It was still smiling widely.

“ A fanatic, huh? It’s good that your brother has such a passion! Hey, where do I find food?” – it turned around. – “Hey, I see another skeleton!  Is that your brother?”  The human waved its arms, jumping up and down a little. “Oiii! We are there, skeleton brother!”

Welp. Time to introduce them came a little earlier.

***

“HUMAN. YOU…” – “Your armor is so cool!”, - Luffy shouted, sparkling eyes trying to take in all of the costume at once, - “Hey, did you make it? I want one too! Ah, but food…no, the armor..no, food! Where can I find food, guys?” – he pleadingly looked at them, stomach growling in agreement. Papyrus stopped in his speech.

“YOU THINK MY ARMOR IS COOL? AH, BUT WAIT, HUMAN. I HAVE TO CAPTURE YOU! I, THE GREAT PAPYRUS, WILL  STOP YOU. I WILL…” – “Who cares about that, I want food-food-food!” – Luffy fell down on the snow, grabbing his stomach. He ate the pie, like, hours ago, and before that he ate nothing at all!

 Papyrus looked at the human. It was a stalemate seemingly.

“HUMAN….HOW DO YOU  REGARD SPAGETTI ?” – he asked, scratching his chin with gloved hand. The human drooled a little and swooned like a human-shaped…well, spaghetti. That decided it.

“NO WORRIES, HUMAN. I WILL FEED YOU, AND THEN I WILL CAPTURE YOU. DO YOU HAVE ANYOBJECTIONS?”

Luffy looked surprised for a second, but then laughed loudly. “So you are a good person, huh? Sure! Where’s food?”

Papyrus blushed lightly, straitening his pose. “OF COURSE I’M GOOD, HUMAN. I’M GREAT, ACTUALLY! NOW, FOLLOW ME. THERE ARE SOME EXTREMELY DIFFICULT PUZZLES ON THE WAY, BUT NO WORRIES! I WILL HELP YOU OVERCOME THEM.”

“Oh, thanks, tall skeleton guy. I hate puzzles!”

Sans looked on, as his brother and the human went on, arguing about crosswords and puzzles in general. He did wonder where Papyrus planned to bring the human. It was worth staying wary, but…it didn’t seem like that reset will end badly.

***

“AND THAT IS OUR HOME, HUMAN! COME IN, I WILL PREPARE SPAGETTI SHORTLY”, - Papyrus opened the door and hurried in the direction of the kitchen.  Luffy came after him, shouting “Sorry for intruding!” to an empty hall. 

***Stop trusting them so much!**

“Aw, but they gave me food!” – Luffy didn’t mind talking to incorporeal voice, but Sans clearly minded him doing so, if that unnerving stare was anything to go by. – “They are nice people!”

***They are MONSTERS, idiot. Not that people are better, but..**

“Wait,” – Luffy turned to Sans, who was watching him from the distance with a little grin, - “YOU guys are monsters?”

“Yeep,” – the skeleton drawled, lifting an eyebrow. They were talking skeletons, what else could they be? And didn’t the boy meet all the random monsters till that moment? – “And what did you think about Snowdrake we met on the way? It’s a joking bird, you know.”

But Luffy was already inconsolable.

“Monsters are big and strong, y’know!”- he showed with his arms the expected size of a monster. The comparison didn’t seem very flattering to Sans. “They should be like RAWR, and then – BAM – and we can fight, and then we eat. Wait, is this As-guy I have to beat weak too?” –Luffy seemed awfully distressed.

“Hey, kiddo, calm down. Pap is pretty strong, for one. He just doesn’t have the stomach for fighting” – Sans winked. The teen started laughing immediately. “As for me…I just don’t have the guts for it.” – Luffy laughed even louder. Sans did have an especially appreciative audience this time. “I have a skele-ton more jokes, kid, so cheer up.”

Luffy wiped a tear from his cheek, still clutching his mid from laughing hysterically. “Man, I really love skull-jokes! You are almost as good as Brook!”

“STOP WITH THOSE TASTELESS JOKES!” – Papyrus shouted from the kitchen. – “HUMAN, THE FOOD IS READY!” Luffy shouted: ”Food-food-food!” while running to the kitchen, with Sans slowly trailing after him.

“Well, bro, it’s alright. After all you don’t have the tongue to taste them,” – the smaller skeleton sat down across Luffy, - “As for you, kid…wait, you have already finished?” Luffy didn’t have time to answer, as he was busy with consuming the whole pan of spaghetti.

“HUMAN….YOU LIKE MY FOOD SO MUCH?” – Papyrus was near tears, - “MAYBE YOU WANT TO BE MY F…” – “MORE FOOD!”

***

**Author's Note:**

> Would be happy to see any corrections, I'm sure there's lots to correct. Anyway, that was fun! Kinda feel my respect for fanfiction writers growing with every symbol.


End file.
